1. Field of the Invention
The invention relates to the field of the in-line roller skates. It relates more particularly to an improved frame for the practice of in-line skating.
2. Description of Background and Material Information
An in-line skate normally has an assembly of several basic elements, including a boot which is attached to a frame that supports a series of aligned wheels. The frame therefore forms the interface between the boot and the wheels. The frame generally includes bridges that receive the boot, these bridges connecting lateral walls serving as supports for the wheels. The frame sustains flexural and torsional stresses that are applied by the skater. It must therefore have sufficient rigidity properties to maintain a correct alignment of the wheels in both the horizontal plane and the vertical plane, in order to prevent sagging, twisting or even lateral deformation during turns.
Various types of frames currently exist. The frames that are the most rigid, but also the most expensive to manufacture, are the frames extruded and machined from a metal section, generally made of aluminum. Thus, a monoblock piece of great rigidity is obtained, which is particularly adapted for competition. The process for producing such frames is described in U.S. Pat. No. 5,388,846, for example. In addition to the cost, there are other drawbacks tied to the monolithic nature of the frame, which provides few possibilities for adjusting the mechanical properties and does not make the frame very shock absorbent.
European Patent Publication No. 0 774 283 discloses a frame that includes separate lateral flanges obtained by stamping sheet metal, then joined by bridges. The desired rigidity is provided by a rib of the frame with a predetermined dimension and position. The production of such a frame nevertheless remains relatively high-cost as a result of the shaping operations and high aluminum consumption.
Also well known are the frames formed of two half-pieces made of injected plastic, joined to one another by complementary fastening means. In general, these frames are more economical to produce; however, they have mediocre mechanical properties.
International Patent Publication No. WO 98/33565 relates to an in-line skate that includes an interface piece arranged between the frame and the boot. The interface piece is attached to the side of the frame by connecting points located between the wheel axles and the bridges of the frame. This structure has the advantage of improving the transfer of forces between the boot and the frame. A structure of this type is nevertheless complicated and expensive to produce since it requires the design of an additional interface piece and a frame made entirely of metal. The excessive thicknesses created between the frame and the interface also have a tendency to elevate the boot with respect to a traditional structure, which is undesirable. These excessive thicknesses also increase the material cost and make the skate heavier.
European Patent Publication No. 0 795 347 discloses a frame that includes two longitudinally spaced blocks joined to one another by sliding lateral rails. A structure of this type allows the length of the frame to be adjusted depending on different shoe sizes. However, such a frame has mediocre rigidity due to the design of the frame in two separate blocks.
U.S. Pat. No. 5,775,706 relates to a skate assembly that includes a boot, a frame having crosswise reinforcing elements and a pair of reinforcing angle brackets connecting the front and rear axes of the frame to the sides of the boot. A structure of this type promotes the transmission of stresses from the boot to the wheels. However, this structure has the drawback of being complex to produce and assemble. Moreover, a structure of this type is not adapted for being associated with a system for rapidly detaching the boot from the frame.
International Patent Publication No. WO 97/33665 relates to a frame for gliding sport articles whose structure includes parts made from materials with different mechanical properties attached to one another at least partially.
U.S. Pat. No. 5,803,466 relates to an in-line skate that includes a frame equipped with a toe plate and a heel plate of the boot, to which independent lateral flanges are detachably attached. The flanges are inserted through two cavities laterally spaced apart and demarcated on each side of the frame by two pairs of edges extending downward from the lower surface of each plate. One of the primary advantages is being able to separate the flanges from the rest of the frame in order to replace them or interchange them. Another advantage is to offer a structure with intermediate plates that favors the weight distribution so as to reinforce the rigidity and strength of the frame. However, a structure of this type does not provide optimal mechanical properties due to the fact that the flanges are only held in place by edges and are locked independently by means of independent screws. Furthermore, the assembly of such a frame is lengthy and not very economical because of the large number of elements, particularly fastening pieces.
Various other frame designs are described in the following documents: UK 18,312; U.S. Pat. No. 578,081; U.S. Pat. No. 593,278; U.S. Pat. No. 2,168,820; U.S. Pat. No. 3,387,852; U.S. Pat. No. 5,380,020; WO 96/22818; U.S. Pat. No. 5,549,310; WO 97/02072; DE 296 12 212 U1; and WO 96/26775. However, all these structures are clearly differentiated from the one offered by the present invention.